[{Au(IPr)}₂(μ‐OH)]X Complexes: Synthetic, Structural and Catalytic Studies

Abstract

The synthesis of a series of dinuclear gold hydroxide complexes has been achieved. These complexes of type [{Au(IPr)}(2)(μ-OH)]X (X=BF(4), NTf(2), OTf, FABA, SbF(6); IPr=2,6-bis(disopropylphenyl)imidazol-2-ylidene; NTf(2)=bis(trifluoromethanesulfonyl)imidate; OTf=trifluoromethanesulfonate; FABA=tetrakis(pentafluorophenyl)borate) are easily formed in the presence of water and prove highly efficient in the catalytic hydration of nitriles. Their facile formation in aqueous media suggests they are of relevance in gold-catalyzed reactions involving water. Additionally, a series of [Au(IPr)(NCR)][BF(4)] (R=alkyl, aryl) complexes was synthesized as they possibly occur as intermediates in the catalytic reaction mechanism. (1)H and (13)C NMR data as well as key bond lengths obtained by X-ray diffraction studies are compared and reveal an interesting structure-activity relationship. The collected data indicate a negligible effect of the nature of the nitrile on the reactivity of [Au(L)(NCR)][X] complexes in catalysis.

Dual Gold Catalysis: σ,π‐Propyne Acetylide and Hydroxyl‐Bridged Digold Complexes as Easy‐To‐Prepare and Easy‐To‐Handle Precatalysts

“…Unfortunately, these ligands turned out to be less efficient and, as well as prolonged reaction times, unacceptable yields were obtained with both of the complexes. In ad- dition, we included a study of hydroxyl-bridged carbene catalyst 13, a species which was first reported by Nolan et al [14] This complex can also be regarded as a dual-activation catalyst, as it provides NHC-Au + and NHC-Au-OH. The latter species has been shown to directly form gold acetylides with terminal alkynes as well.…”

Ligand Exchange at a Gold(I) Carbene Complex

“…Gold NHC complexes are currently of special interest due to their application as catalysts for selected homogeneous transformations [36] and as metallodrugs in antitumor therapy [37,38]. These successful applications are based on the inertness of the Au-C NHC bond in complexes of type [Au(NHC)L] n+ , which also allows substitution reactions of the co-ligand L for halides [39], nitrogen [40] or phosphorus donors [41,42].…”

Encapsulation Studies of Cationic Gold Complexes within a Self‐Assembled Hexameric Resorcin[4]arene Capsule

“…Furthermore, the value calculated for the diffusion coefficient of [1-OH 2 ] + ʚ3 6 (2.7 Ϯ 0.2 ϫ 10 -10 m 2 s -1 ) is in line with that previously reported for the chloroform-filled hexameric resorcinarene assembly (2.8 ϫ 10 -10 m 2 s -1 ). Formation of μ-OH dimeric gold complexes induced by a simple water washing procedure as reported by Nolan et al [25] cess. [25] Nolan noted that by simply washing a CH 2 Cl 2 solution of complex [1-NCMe] + [BF 4 ]with water μ-OH pseudo-dimer [4] + [BF 4 ]was produced in high yield.…”

“…This helps to confirm that the gold complex and the hexamer correspond to the same supramolecular aggregate. [25] Nolan noted that by simply washing a CH 2 Cl 2 solution of complex [1-NCMe] + [BF 4 ]with water μ-OH pseudo-dimer [4] + [BF 4 ]was produced in high yield. [24] At the time these experiments were being performed, Nolan et al reported the preparation of μ-OH pseudo-dimeric gold complex 4 + (Scheme 2).…”